TSLP-Associated Allergic Conjunctiva Inflammation in a Novel Mouse Model Induced by Dual Antigens: Orchard Grass and Alternaria.

Abstract

PURPOSE: To investigate innate and adaptive immune responses in allergic conjunctivitis induced by simultaneous sensitization with Orchard grass andantigens. MATERIALS AND METHODS: An experimental allergic conjunctivitis (EAC) mouse model was developed by instilling mixed antigen solutions of Orchard grass andantigens after sensitizationintraperitoneal administration of a mixed antigen solution. BALB/cj mice were divided into four groups based on sensitization and number of antigen eye drop instillations: (1) A1 group (single instillation without intraperitoneal administration), (2) S1 group (single instillation with intraperitoneal administration), (3) M1 group (three instillations with intraperitoneal administration), (4) C group (negative control with receiving neither instillation nor intraperitoneal administration). Clinical observations and histological examinations for eosinophils were performed, and eosinophil density in the conjunctival tissue was quantified. Gene expression levels of thymic stromal lymphopoietin (TSLP), interleukins (IL-4, IL-5, IL-13, IL-16, and IL-33), and CCL11/eotaxin-1 in the conjunctiva were evaluated using real-time reverse transcriptase polymerase chain reaction. RESULTS: The clinical symptoms of allergic conjunctivitis were observed in the A1, S1, and M1 groups. Eosinophil density at 1&#x2009;h after the last instillation was significantly higher in the A1, S1, and M1 groups compared to the C group (&#x2009;<&#x2009;0.01), with the M1 group showing higher density than the S1 group (&#x2009;<&#x2009;0.01). Conjunctival TSLP messenger RNA (mRNA) expression levels were increased in the sensitized (S1 and M1) groups compared to the C group (&#x2009;<&#x2009;0.01 and&#x2009;<&#x2009;0.05, respectively), with the M1 group exhibiting higher expression than the S1 group (&#x2009;<&#x2009;0.01). Additionally, mRNA expression levels of IL-16 and CCL11 in the M1 group were significantly higher than those in the A1 group. CONCLUSIONS: Allergic conjunctivitis induced by Orchard grass andantigens is characterized by early eosinophil infiltration, and TSLP upregulation exacerbates the allergic inflammation in the conjunctiva.